This epidemiologic study is a multidisciplinary approach to elucidate the relationship of early childhood levels of blood lipoproteins, blood pressure and anthropometric measures to the development of hyperlipidemia and hypertension in late childhood and early adult life. An entire school district of approximately 6,000 school age children in Muscatine, Iowa have had their plasma lipids, blood pressure, heights, weights and triceps skinfold thickness measured on three occasions over a five year period. Thus, the entire distribution of these variables are known at each school age level, and the relationship of the measurements made on the same individual on repeated occasions can be estimated. It plans to examine the familial and psychologic factors relating to the distribution of blood pressure, and to study cardiac output and vascular resistance not only as they exist across the distribution of blood pressure but also as they are effected by orthostatic stress and sodium intake.